I don't know how this has happened, but the early Triamps were wildly different sounding
The highest gain channels have always been compressed sounding, but on the mark I it was smooth and refined and rich sounding, kind of like a kittyhawk or something like that, and the orange channels were a very convincing superlead or jmp sound. On the newer models its like it keeps getting grainier and more scooped every revision, until now, where the modern ones almost sound like a solid state gain sound like a randall. It's so grainy, weedy, and thin that it's ridiculous - the only way it sounds good is with a 7 string or something where you need to cut all the low end out anyways.
I don't know what happened to H&K but their products have really taken a huge downturn in actual sound the past 20 years, its kind of wild.